Field of the Invention
The present invention relates to a substrate loading device that loads a plurality of substrates.
Description of the Related Art
As a detailed example of a flat display device, there are a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), an organic light emitting diode (OLED), and the like, Here, each of the flat display devices essentially has flat transparent substrates that face and are attached to each other and have a fluorescent and/or polarization material layer there between.
In a process of manufacturing a flat display device, a large number of processes are included, such as a cleaning process, an attaching process, a cutting process, deposition process to deposit a thin film made of predetermined material on a substrate, a photolithography process to expose a selected portion of the thin film, and an etching process to implement a desired thin film pattern by removing the exposed portion of the thin film.
Meanwhile, substrates for manufacturing a flat display device may be kept in a substrate loading device such as a cassette to temporarily keep, transport or move into each process. Particularly, the substrate loading device may be placed in a thermal processing device, such as a hardening furnace in a state in which the substrates are loaded. In view of the process characteristics of the hardening, since much time is consumed, the substrate loading device must be configured to process a plurality of semiconductor substrates at a time in order to provide for sufficient throughput for a manufacturing line environment.
However, in the case in which the substrate is heated for a long time, the substrate may bend, warp and/or sag. When such bending, warping and sagging of the substrates occur, defects can be generated.
In accordance with the recent trend toward thinness and increased surface area of the substrate, the warpage problem of the substrate is further intensified, thereby causing deterioration of productivity, yield and reliability of in the manufacturing process.